Tribological Properties of Polyacetal/Polyethylene (LDPE, HDPE, HMWHDPE) Blends

To improve tribological properties of polyacetal (POM), blends with polyethylene (PE) were prepared by extrusion and studied. Three types of PE, i.e., low density polyethylene (LDPE), high density polyethylene (HDPE), and high molecular weight high density polyethylene (HMWHDPE) were employed in the present study. Each specimens in the shape of a pipe containing one of these PE types were rubbed against a rotating carbon steel (S45C) slider under unlubricated conditions. Observation with an electron probe X-ray microanalyzer (EPMA) revealed that the specimens had sea-island structures in which polyethylene particles were finely dispersed in the POM matrix. An optical microscope observation indicated that these polyethylene particles mainly bore the load applied to the frictional surface. The wear volume in both the case where LDPE was blended and that where HDPE was blended showed a remarkable decrease, the blending effect of HDPE being much greater than that of LDPE. The coefficient of friction in both of these cases became smaller, the values indicated becoming nearly the same. On the other hand, contrary to expectations, blending with HMWHDPE resulted tribological properties which were handly improved.